1. Field of the Invention
The present invention relates to masking plugs for complex parts. In particular, the present invention relates to self-adjusting masking plugs for complex parts which are adapted to be fit into similarly dimensioned parts which have the same dimensions, but which have varying tolerances.
2. Background of the Invention
When a complex aerospace, defense, manufacturing, or industrial machine part or the like is manufactured, the part may have areas which are intended to have exposed machine surfaces as well as surfaces which are coated with various coating materials (primer, paints, powder coat, rust inhibitors, sealants, etc.) Typically, the portion of the part intended to be left exposed without coating is masked with tape and materials, such as plastic sheets or paper. This conventional technique is the most common; however, when dealing with large production runs of the same parts, conventional masking becomes a measurable component is with respect to the manual labor and handling of the part. Also, since the quality of the conventional technique of masking is dependent on the individual performing the job, the results (i.e., quality of mask job) is prone to varying.
In certain situations in which numerous complex parts having the same dimensions are manufactured, to save time in the masking process, a masking plug may be fabricated, wherein the plug may be used repetitively for each complex part. For instance, many parts may have features such as holes, bores, valleys, voids, journals, cylinders, sealing surfaces, etc. which may be easily filled with a masking plug before the coating process takes place. The plug may be made from various materials, such as foam, rubber, plastic, composites, wood or any material which can be formed into a durable object which may be repetitively positioned within the area to be protected from coating without damaging the part surfaces. Once the complex part has been coated, the masking plug is removed from part.
A drawback with masking plugs, however, is that many times the holes, bores, valleys, voids, journals, cylinders, sealing surfaces, etc. [also hereinafter referred to as “masked areas” or “areas intended to be masked], may not always be the exact size. That is to say, even though the complex parts may be built from the same blueprints which have the same dimensions, the tolerances of such parts sometimes vary. For instance, areas not intended to be machined to precise dimensions tend to be manufactured to less precise dimensions and tolerances. And as a result, many times the masking plug does not properly fit into the masked area. Or many times, the masking plug fits, but leaves larger then acceptable gaps between the part and the plug. In this situation, the coating is not blocked by the masking plug and areas intended to be masked end up being inadvertently coated and the removal of the inadvertent coated areas adds cost to the manual labor component.
It would advantageous to provide a masking plug for complex parts which overcomes some of the fallbacks found with the aforementioned methods of masking. In particular, it would be beneficial to design a masking plug which is adapted to be received into an intended masking area, while at the same time, has a self-adjusting feature which allows the size the masking plug to expand and contract. Such an adjustable masking plug would help eliminate the unwanted gaps created as a result of an ill-fitting masking plug.